The present invention relates in general to systems for the regulation and control of chemical processes which involve the production of gas, for example processes in cement furnaces.
Systems are known for the extraction of gases from a furnace, provided with probes to be mounted within the furnace, in which the gases extracted are conveyed to analyser devices.
For the extraction of the gases such systems utilise a small pump of low power and low pressure, in suction (through the probe). This implies treating the gases hot/moist, giving rise to corrosive acids which attack the couplings, the tubes and the various components involved in the flow of gas, aggravating the situation. For the purpose of avoiding the precipitation of condensate in the system (because it draws in hot/moist gas), it is necessary to heat the aspiration tube, the filter and the tube but with declining results (problems of packing, acids etc).
The probes further have serious problems of blockage of the gas aspiration tube, which make operation unreliable.
Moreover, in traditional probes the filtering of dust is achieved solely by the filter which is overloaded and becomes clogged. The cleaning of the probe is achieved by a washing cycle with compressed air (programmable) but often it is insufficient fully to restore it and, moreover, this introduces contamination into the gas to be analysed.
Because of these problems the values of the furnace gas analysis are approximate and irregular, leading to a misunderstanding of a correct management of the line, especially in the presence of alternative fuels. With these latter, even the best probes currently in commercial use show their limits. Only by meticulous and continuous surveillance and maintenance by man is it possible to obtain results, which even then are only just sufficient.